C O M M U N I C A T I O N S
Figure 1. Calculated (top, blue) and experimental (bottom, red) ESI-MS spectra (5+) and molecular force field models of (A) double triangle 4, (B) double
rhomboid 7, and (C) triple rhomboid 8.
We then tried to extend this protocol from triangular to rhomboidal
systems. Tetrapyridine donor 2 can also be used as a linker in the
formation of double- and triple-rhomboid structures. Whereas donor
1, with two pyridine arms at an angle of 60° from each other, was
used in the formation of double triangle 4, a different bispyridine (5)
with an angle of 120° between coordination sites was required for the
formation of multirhomboid polygons such as 7 and 8. Reacting a
mixture of donors 2 and 5 with 180° di-Pt(II) acceptor 6 in a 1:2:4
ratio gave double rhomboid 7. Moreover, when the ratio was changed
to 1:1:3, triple rhomboid 8 was readily obtained (Scheme 2).
In conclusion, new self-assembled fused metallacyclic polygons
have been synthesized through stoichiometric and structural control
of multicomponent mixtures of different pyridyl donors and platinum
acceptors. These studies have revealed that single supramolecular
species can be formed from multicomponent self-assembly and that
the shape of the product polygons can be controlled simply by changing
the ratio of individual components, thus demonstrating that various
multisupramolecular architectures can be synthesized from multiple
diverse tectons via a dynamic coordination-driven self-assembly
process when appropriate components are mixed in a controlled ratio.
To the best of our knowledge, this represents the first report of the
formation of predesigned, discrete products using multiple different
tectons via the coordination-driven methodology.
A single set of signals from the donor and acceptor units in the 1H
NMR spectra of 7 and 8 indicated the formation of a single, discrete,
highly symmetric supramolecular assembly for each reaction. For both
7 and 8, two 31P signals are predicted, but only a single signal was
observed for 7, whereas two overlapping signals were observed for 8,
indicating as expected a close similarity of the two phosphorus
environments in both 7 and 8 (see the SI). In the ESI mass spectrum
of double rhomboid 7, peaks at m/z 2070.5 and 1182.3 attributable to
[M - 3OTf]3+ and [M - 5OTf]5+, respectively, were observed (Figure
1 and Figure S8 in the SI). The full spectrum showed that no other
products existed in the solution of double rhomboid 7. Furthermore,
the ESI mass spectrum for triple rhomboid 8 revealed peaks at m/z
1847.6 and 3179.3, corresponding to [M - 5OTf]5+ and [M -
3OTf]3+, respectively (Figure 1 and Figure S9 in the SI). The full
spectrum of triple rhomboid 8 indicated that there were no other
products in the complex mixture, including the smaller double
rhomboid 7. Furthermore, pulsed-gradient spin-echo experiments were
used to find the diffusion coefficients, D. The ratio of D values for 7
and 8 was 1.6:1, indicating that their hydrodynamic diameters lie in
the inverse ratio of 1:1.6 (since D is inversely proportional to the
molecular size). Molecular force field simulations showed outer
diameters of ∼5.5 and ∼8.6 nm for 7 and 8, respectively, which are
in relative, qualitative agreement with the experimentally determined
ratio (see the SI). Consequently, we have demonstrated that it is
possible to control the shape and size of supramolecules simply by
tuning the relative ratio of multicomponent donor/acceptor mixtures.
All attempts to obtain the crystal structure of higher-order polygons
4, 7, and 8 were unsuccessful. Therefore, molecular force field
simulations were used to gain further insight into their structural
characteristics (Figure 1 and Figure S10 in the SI). A 1.0 ns molecular
dynamics simulation (MMFF force field) was used to equilibrate the
supramolecules, and then the energies of the resulting structures were
minimized to full convergence. Rotation around the single bond of
the biphenyl moiety of 2 makes 4, 7, and 8 nonplanar.
Acknowledgment. P.J.S. thanks the NIH (Grant GM-057052)
for financial support.
Supporting Information Available: Synthesis and analytical data
for 2, ESI mass spectra, and molecular modeling procedures. This
References
(1) (a) Li, S.-S.; Yan, H.-J.; Wan, L.-J.; Yang, H.-B.; Northrop, B. N.; Stang,
P. J. J. Am. Chem. Soc. 2007, 129, 9268. (b) Seeman, N. C.; Belcher, A. M.
Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 6451. (c) Balzani, V.; Credi, A.;
Venturi, M. Chem.sEur. J. 2002, 8, 5524.
(2) (a) Stang, P. J.; Olenyuk, B. Acc. Chem. Res. 1997, 30, 502. (b) Leininger,
S.; Olenyuk, B.; Stang, P. J. Chem. ReV. 2000, 100, 853. (c) Seidel, S. R.;
Stang, P. J. Acc. Chem. Res. 2002, 35, 972. (d) Schwab, P. F. H.; Levin,
M. D.; Michl, J. Chem. ReV. 1999, 99, 1863. (e) Holliday, B. J.; Mirkin,
C. A. Angew. Chem., Int. Ed. 2001, 40, 2022. (f) Cotton, F. A.; Lin, C.;
Murillo, C. A. Acc. Chem. Res. 2001, 34, 759. (g) Fujita, M.; Tominaga,
M.; Hori, A.; Therrien, B. Acc. Chem. Res. 2005, 38, 369. (h) Fiedler, D.;
Leung, D. H.; Bergman, R. G.; Raymond, K. N. Acc. Chem. Res. 2005, 38,
349. (i) Ward, M. D. Chem. Commun. 2009, 4487.
(3) (a) Stulz, E.; Ng, Y.-F.; Scott, S. M.; Sanders, J. K. M. Chem. Commun. 2002,
524. (b) Schmittel, M.; Mahata, K. Angew. Chem., Int. Ed. 2008, 47, 5284.
(c) Schmittel, M.; Kalsani, V.; Kishore, R. S. K.; Co¨lfen, H.; Bats, J. W.
J. Am. Chem. Soc. 2005, 127, 11544. (d) Schmittel, M.; Mahata, K. Inorg.
Chem. 2009, 48, 822. (e) Yang, H.-B.; Ghosh, K.; Northrop, B. H.; Zheng,
Y.-R.; Lyndon, M. M.; Muddiman, D. C.; Stang, P. J. J. Am. Chem. Soc.
2007, 129, 14187. (f) Ghosh, K.; Yang, H.-B.; Northrop, B. H.; Lyndon,
M. M.; Zheng, Y.-R.; Muddiman, D. C.; Stang, P. J. J. Am. Chem. Soc.
2008, 130, 5320. (g) Baxter, P.; Lehn, J.-M.; DeCian, A.; Fischer, J. Angew.
Chem., Int. Ed. Engl. 1993, 32, 69. (h) Chichak, K. S.; Cantrill, S. J.; Pease,
A. R.; Chiu, S.-H.; Cave, G. W. V.; Atwood, J. L.; Stoddart, J. F. Science
2004, 304, 1308. (i) Cho, Y. L.; Uh, H. S.; Chang, S.-Y.; Chang, H.-Y.; Choi,
M.-G.; Shin, I.; Jeong, K.-S. J. Am. Chem. Soc. 2001, 123, 1258.
(4) (a) Yang, H.-B.; Ghosh, K.; Northrop, B. H.; Stang, P. J. Org. Lett. 2007,
9, 1561. (b) Addicott, C.; Das, N.; Stang, P. J. Inorg. Chem. 2004, 43, 5335.
(c) Northrop, B. H.; Yang, H.-B.; Stang, P. J. Inorg. Chem. 2008, 47, 11257.
(d) Zheng, Y.-R.; Yang, H.-B.; Northrop, B. H.; Ghosh, K.; Stang, P. J.
Inorg. Chem. 2008, 47, 4706.
(5) Yamanoi, Y.; Sakamoto, Y.; Kusukawa, T.; Fujita, M.; Sakamoto, S.;
Yamaguchi, K. J. Am. Chem. Soc. 2001, 123, 980.
JA903330J
9
J. AM. CHEM. SOC. VOL. 131, NO. 34, 2009 12029